Seating unit comprising two adjacent, pivotal support elements

ABSTRACT

A seating unit having two adjacent and mutually pivotal support elements 3, 4) pivotal between an initial position and a maximum flexed position. A spring element (12) is secured between the support elements (3, 4) and biases the support elements (3, 4) into the initial position. The spring element (12) comprises a base member (13) arranged in an area between the support elements (3, 4). At least one engagement element extends from the base member (13) into cavity (14, 15) in one of the support elements (3, 4) such that the support elements (3, 4) may pivot relative to each other. The engagement element is provided with a rigid stop (17, 17&#39;) projecting from the base member (13) to define the maximum flexed position of the support elements. The engagement element is further provided with a leaf spring (18, 18&#39;; 68) to restore the support elements (3, 4) to their initial position.

TECHNICAL FIELD

The invention relates to a seating unit comprising two adjacent andmutually pivotal support elements pivotal around an axis between aninitial position and a maximal flexed position and a spring elementsecured between the support elements and provided with a leafspring-like means biassing the support elements into the initialposition, the spring element comprising a base member arranged in theadjacent area of the support elements and engagement means provided oneach side of the base member and engaging each their own support elementat least one engagement means extending from the base member and into acavity in one of the support elements such that the support elements maypivot relative to each other.

BACKGROUND ART

Seating units having a pivotal, flexible, upper backrest element and/ora front, pivotal, flexible seat element are known to enhance the seatingcomfort when the user adopts different sitting postures.

Thus, U.S. Pat. No. 4,498,702 discloses a seating unit having a frontseat element connected to the rest of the seat by means of twointerspaced leaf springs maintaining the front seat element in aninitial position. When the front seat element is loaded, it may flexdownwardly to a maximum flexed position determined by means of aseparate stop.

Furthermore, U.S. Pat. No. 4,603,904 discloses a seating unit comprisinga lower backrest frame part formed of two upstanding frame members andan upper backrest frame part formed of two upstanding frame membersarranged in continuation in the lower frame members. A flexible springelement is secured between the two pairs of the frame members to providea flexing of the upper backrest frame part and thus of the backrestrelative to the lower backrest frame part. Each flexible spring elementcomprises a plastic strut provided with a centrally arranged wire andmaintaining the strut under compression and limiting the elongationthereof, when the backrest is loaded during use of the seating unit.

Finally, U.S. Pat. No. 4,869,552 and U.S. Pat. No. 5,039,163 bothdisclose a seating unit of the above type except that the flexiblespring elements between the two backrest parts each comprises a leafspring whose opposite ends are fixed to each their own U-shaped holdermembers at the inner end thereof, one open end thereof facing toward theother. At the open ends the holder members are provided with restrictiveflanges extending laterally outwardly and adapted to interengage todefine the maximum flexed position between the two backrest frame parts.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to provide a seating unit of the abovetype comprising a simply shaped spring element to define the initialposition and the maximum flexed position of the two support elements.

The seating unit according to the invention is characterised in

that said at least one engagement means is provided with a rigid stopmeans projecting from the base member and being pivotally received inthe associated cavity for defining the maximum flexed position byabutting one inner face (21,21') of the cavity, and

that in order to bias the support elements (3,4) into their initialpositionthe spring means (18, 18'; 68) of said at least one engagementmeans is provided with a free end co-acting with said one inner face(21,21') abutting the stop means in the maximum flexed position.

In that the projecting engagement means of the spring element and thusits stop means and spring means all are received in a cavity and thus ineffect concealed, many options as to the shape and dimensioning of theseare rendered without effecting the appearance of the seating unit.

According to the invention, in order to define the initial position thestop means may be adapted to abut an inner face of the cavity oppositethe inner face of the cavity it abuts in the maximum flexed position andthe spring means may be prestressed in the initial position. It is thusensured that the support elements only pivot in the desired directionrelative to each other and that due to the spring loading of the springmeans said elements always revert to their initial position when theyare not loaded, even if the spring means gradually might lose some ofits elastic force.

Moreover, according to the invention the leaf spring-like means mayadvantageously be slightly curved in its initial position, by beingbowed away from the inner cavity face with which it co-acts. Due to itsslightly curved state, when stressed the leaf spring-like member isstraightened and its length thus increased. The feature is particularlyadvantageous in a further embodiment of the invention in which thespring means is in retaining engagement with the inner cavity face withwhich it co-acts.

Furthermore, according to the invention the engagement means of thespring element may be provided with outer guide faces beingperpendicular to the pivot axis and adapted to co-act with oppositeguide faces of the cavity for a controlled flexing of the respectivesupport element in relation to the projecting stop means.

Moreover, according to the invention the stop means may be formed of twointerspaced legs extending from the base member, the spring means beingarranged therebetween.

According to the invention the spring element may further be providedwith engagement means projecting from each side of the base member andreceived in a respective cavity of the two support elements.Consequently, the flexing of the support elements relative to each otheris obtained by a flexing of each support element relative to the stopmeans of the engagement means interengaging said element.Correspondingly, the deformation of the spring element caused by theflexing is shared by the spring means of the two engagement means. Thisembodiment is particularly advantageous with a view to maintaining theability of the spring element to restore the support elements to theirinitial position.

Finally, in connection with the above embodiment of the invention thespring element may advantageously be shaped symmetrically reversed inrelation to the base member.

The invention further relates to a spring element for use in a seatingunit comprising two adjacent and mutually pivotal support elementspivotal around an axis between an initial position and a maximal flexedposition, said spring being provided with a leaf spring-like meansadapted to bias the support elements into the initial position, thespring element comprising a base member adapted to be arranged in anarea between the support elements and engagement means provided on eachside of the base member and adapted to interengage support element, atleast one engagement means extending from the base member to be receivedsuch in a cavity in one of the support elements so that the supportelements may pivot relative to each other.

The spring element according to the invention is characterised in

that said at least one engagement means is provided with a rigid stopmeans projecting from the base member and being pivotally received inthe associated cavity for defining the maximum flexed position byabutting one inner face of the cavity, and

that in order to bias the support elements into their initial positionthe spring means of said at least one engagement means is provided witha free end co-acting with said one inner face abutting the stop means inthe maximum flexed position.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in greater detail in the following withreference to the particularly preferred embodiments and accompanyingdrawings, in which

FIG. 1 illustrates a seating unit according to the invention in the formof a chair comprising two seat elements pivotal relative to each otherand two back elements pivotal relative to each other, seen partly in aside elevational view and partly in section,

FIG. 2 is a vertical, partly sectional view on an enlarged scale throughthe two seat element in an initial position and from which a springelement according to the invention also appears,

FIG. 3 is a vertical, partly sectional view through the two seatelements in a maximum flexed position,

FIG. 4 is a side elevational view of the spring element according to theinvention,

FIG. 5 is a top view of the spring element according to the invention,the spring element being arranged between the two seat elements shown insection,

FIG. 6 is the same partly sectional view as in FIG. 2 through twomutually pivotal seat elements in their initial position, a secondembodiment of the spring element according to the invention beingsecured therebetween, and

FIG. 7 corresponds to FIG. 3 and illustrates the seat elements shown inFIG. 6 in their maximum flexed position.

BEST MODE FOR CARRYING OUT THE INVENTION

The chair shown in FIG. 1 comprises a seat 1 and a back 2. The seatcomprises a main seat element 3 and an outer seat element 4 pivotalrelative hereto. The main seat element 3 is fixedly connected with aseat support 5 wherefrom four legs 6 extend downwardly. The back 2comprises a lower back element 7 and an upper back element 8 pivotalrelative thereto. The main seat element 3 and the lower back element 7are interconnected by means of a frame element comprising twointerspaced, bent tubes 9 of a square section. Each tube 9 extendsthrough the entire main seat element 3 at one end and through the entirelower back element 7 at the other end. In registry with the tubes 9 twointerspaced tubes 10 are arranged in the outer seat element 4.Correspondingly, in registry with the tubes 9 two interspaced tubes 11are arranged in the upper back element 2. In the adjacent area of thetwo seat elements 3,4 and the two back elements 7,8, a spring element 12is arranged between the cavities formed by the tubes 9, 10 and 9, 11respectively. The spring element 12 is described in detail withreference to the spring element arranged between the seat elements 3, 4,as the spring element arranged between the back elements 7, 8 is formedin a corresponding manner.

As it appears from FIGS. 2 to 5 the spring element 12 comprises adisk-like, rectangular base member 13 abutting in the initial positionshown in FIGS. 2 and 5 the edge by the cavity 14 and 15 respectivelyformed of the tubes 9 and 10 in the main seat element 3 and the outerseat element 4. The spring element 12 is shaped symmetrically reversedaround the base member 13 and an engagement means extends into the twocavities 14,15 from each side of said base member. Each engagement meanscomprises two interspaced, rigid legs 16,16',17,17' and a leafspring-like means 18, 18' arranged between said legs. At its outer endeach leaf spring-like 18, 18' is provided with a projection 19, 19'engaging a recess 20, 20' in the upper face 21,21' of the cavity 14, 15.When comparing FIG. 2 with FIG. 4, it appears that the leaf spring-likemeans 18, 18' of the spring element 12 are prestressed and act to bringthe two seat elements 3,4 into the initial position shown in FIG. 2.

For definition of the initial position, the lower edge faces 22, 22' ofthe legs 16, 16', 17, 17' abut the lower surfaces 23, 23' of thecavities 14, 15. The seat ele25 ments 3,4 may pivot relative to eachfrom the initial position to a maximum flexed position shown in FIG. 3,the force from the leaf spring-like means 18,18' being overcome. Theupper edge faces 24, 24' of the legs 16, 16'; 17, 17' abut the uppersurface 21,21' of the cavities 14,15 in the maximum flexed position.

Moreover, each leg 16, 17, 16', 17' comprises an outer lateral face 25,26, 25', 26'abutting a respective lateral face 27, 28, 27', 28' of eachcavity 14, 15. The lateral faces act as guide faces when the two seatelements 3,4 are flexed relative to each and thus when the legs 16, 16',17, 17' of the engagement means are pivoted relative to the cavities14,15 of the seat elements 3,4.

The pivoting/flexing between the two seat elements 3, 4 takes placearound two parallel axes 29, 29' defined by the two transverse edges 30,30' between the lateral faces 31, 31' of the base member 13 and itslower edge face 32. During flexing the leaf spring-like means 18,18'being slightly curved in their initial position (bowed away from innerfaces 21, 21') are straightened, whereby these are essentiallyrectilinear in the maximum flexed position. Due to the straightening ofthe leaf spring-like means 18, 18' the distance between the engagementpoint of the spring means 18, 18' with the cavity 14, 15 (defined by theengagement of the projection 19,19' with the recess 20, 20') and theaxis 29,29' respectively remains essentially constant during theflexing.

The spring element 12 is made integrally of plastic, preferably ofreinforced plastic, e.g. glass fibre reinforced polyamide containinge.g. 30% glass fibres.

The embodiment of a spring element 62 shown in FIGS. 6 and 7 is securedbetween two seat elements 3, 4 formed as shown in FIGS. 1 to 5, forwhich reason these are not described further. The spring element 62 isprovided with a first engagement means extending from the side of thebase member 63 shown on the right-hand side of the Figure and is inretaining engagement with the cavity 14 in the seat element 3. A secondengagement means extends from the other side of the base member 63, i.e.shown on the left-hand side on the Figure, to engage the cavity 15 inthe seat element 4. This second engagement means is shaped in a mannercorresponding to the engagement means of the spring element 12 describedabove. The second engagement means thus comprises two interspaced, rigidlegs 67 extending from the base member 63 and a leaf spring-like means68 arranged therebetween and also extending from the base member 63. Theleaf spring-like means 68 engages the recess 20' in the upper surface21' of the cavity by means of a projection 69 provided at its outer end.Each leg 67 is provided with a lower edge face 72 engaging the lowersurface 23' of the cavity 15 in its initial position. Furthermore, eachleg is provided with an upper edge face 74 engaging the upper surface21' of the cavity 15 in its maximum flexed position shown in FIG. 7.

As the engagement means engaging the main seat element 3 is firmlyinterconnected therewith, the pivoting/flexing between the two seatelements 3,4, only takes place between the seat element 4 and the rigidlegs 72 of the second engagement means around an axis 79. As describedabove, the axis 79 is defined by a transverse, lower edge between thelower edge face 82 of the base member 63 and the lateral face 81 of thebase member 63 from which the rigid legs 67 and the leaf spring-likemeans 68 extend.

The spring element 62 is likewise made integrally of plastic, preferablyreinforced plastic, such as polyamide containing e.g. 30% glass fibres.

What is claimed is:
 1. A seating unit comprising two adjacent andmutually pivotal support elements (3, 4) pivotal around an axis betweenan initial position and a maximum flexed position and a spring element(12; 62) secured between the support elements (3, 4) and provided with aleaf spring means (18, 18'; 68) biassing the support elements (3, 4)into the initial position, the spring element (12; 62) comprising a basemember (13; 63) arranged in an area between the two adjacent supportelements (3, 4) and engagement means provided on each side of the basemember and engaging respective support elements (3, 4), at least oneengagement means extending from the base member (13; 3) and into acavity (15) in one of the support elements (4) such that the supportelements (3, 4) may pivot relative to each other, characterized inthatsaid at least one engagement means is provided with a rigid stop means(16, 17, 16', 17'; 67) projecting from the base member and beingpivotally received in said cavity (14, 15) for defining the maximumflexed position by abutting a first inner face (21, 21') of the cavity(14, 15), that in order to bias the support elements (3, 4) into theirinitial position, the leaf spring means (18, 18'; 68) is provided with afree end co-acting with said first inner face (21, 21') abutting thestop means in the maximum flexed position, and that in order to definesaid initial position, said stop means is adapted to abut a second innerface (23, 23') of the cavity opposite the first inner face (21, 21') ofthe cavity (14, 15), said spring means (18, 18'; 68) being prestressedin said initial position.
 2. A seating unit as claimed in claim 1,characterised in that in order to define the initial position the stopmeans is adapted to abut an inner face (23,23') of the cavity oppositethe inner face (21, 21') of the cavity (14, 15) it abuts in the maximumflexed position and that the spring means (18, 18'; 68) is prestressedin the initial position.
 3. A seating unit as claimed in claim 1,characterised in that in said initial position, the leaf spring means(18, 18'; 68) is slightly bowed away from said first inner face (21,21') of said cavity.
 4. A seating unit as claimed in claim 1,characterised in that the spring means (18, 18'; 68) is in retainedengagement with the first inner cavity face (21, 21').
 5. A seating unitas claimed in claim 1 characterised in that the engagement means of thespring element (12,62) is provided with outer guide faces (25,26, 25',26) being perpendicular to the pivot axis and adapted to co-act withopposite guide faces (27, 28, 27', 28') of said cavity (14, 15) for acontrolled flexing of the respective support element (3,4) in relationto the projecting stop means (16, 17, 16', 17'; 67).
 6. A seating unitas claimed in claim 1, characterised in that the stop means is formed oftwo interspaced legs (16, 16', 17'; 67) extending from the base member(13;63), the spring means (18, 18'; 68) being arranged therebetween. 7.A seating unit as claimed in claim 1, characterised in that the springelement (12) is provided with engagement means projecting from each sideof the base member (13) and received in a respective said cavity (14,15)of the two support elements (3,4).
 8. A seating unit as claimed in claim7, characterised in that the spring element (12) has a symmetricallyreversed shape in relation to the base member (13).
 9. A spring element(12, 62) for use in a seating unit comprising two adjacent and mutuallypivotal support elements (3, 4) pivotal around an axis between aninitial position and a maximum flexed position, said spring elementbeing provided with a leaf spring means (18, 18'; 68) adapted to biasthe support elements (3, 4) into the initial position, the springelement (12; 62) comprising a base member (13; 63) adapted to bearranged in an area between the two adjacent support elements (3, 4) andengagement means provided on each side of the base member (13, 63) andadapted to engage said support elements (3, 4), at least one engagementmeans extending from the base member (13; 63) so as to be received in acavity (14, 15) in one of the support elements (3, 4) such that thesupport elements (3, 4) may pivot relative to each other, characterisedinthat said at least one engagement means is provided with a rigid stopmeans (16, 17, 16', 17';67) projecting from the base member and beingpivotally received in a respective cavity (14, 15) for defining themaximum flexed position by abutting a first inner face (21, 21') of therespective cavity (14, 15), that in order to bias the support elements(3, 4) into their initial position the spring means (18, 18'; 68) ofsaid at least one engagement means is provided with a free end forco-acting with said first inner face (21, 21') abutting the stop meansin the maximum flexed position, and that in order to define the initialposition, the stop means is adapted to abut a second inner face of theassociated cavity opposite said first inner face, the spring means beingprestressed in the initial position.
 10. A spring element as claimed inclaim 9, characterised in that the stop means is formed by twointerspaced legs (16, 16', 17'; 67) extending from the base member (13;63), the spring means (18, 18'; 68) being arranged therebetween.
 11. Aspring element as claimed in claim 9, characterised in that the springelement (2) is provided with engagement means projecting from each sideof the base member (13).
 12. A spring element as claimed in claim 9,characterised in that the spring element (2) has a symmetricallyreversed shape in relation to the base member (13).